Centrifugal pump



April 28, 1953 J. M. ROTH CENTRIFUGAL PUMP Filed April 8. 1950 l 34- m g 2 n l2. M (T'TH l I4 )4 FIG. I

JAY M. ROTH ATTORNEYS Patented Apr. 28, 1953 CENTRIFUGALPUMP Jay M. Roth, Uhrichsville, Ohio, assignor to Mechanisms Company, Uhrichsville, Ohio, a

corporation of Ohio Application 'April 8, 1950, Serial No. 154,832

' This invention relates to centrifugal pumps and, more particularly, is concerned with pumpsof'this type adapted to be driven by an electric motor or other prime mover. v

Various types and sizes of centrifugal pumps have been provided heretofore. However, many known pumps'have a relatively low efiiciency, and areoften characterized by high manufacturing and maintenance costs. Bearing means are usually'required between therotary impeller and the casing, and a spline" typeand/or universal joint 'eeupun'g miis generally be used between the impeller shaft and the prime mover or motor shaft in order to maintain impeller-to-casing clearan'ces within proper limits. Impeller-to casing clearances in known centrifugal pumps are usually rather critical, which necessitates careful attention to machining and working tolerances.

It is the general object'of my invention to avoid and overcome the foregoing and other difiiculties of and objections to known centrifugal pump constructions by the provision of an improved, relatively inexpensive, easily constructed and long-lived centrifugal pump characterized, by relatively high eiiiciencies and lack of close tolerances. g

Another object of my invention is to provide a centrifugal pump assembly in which the rotary impeller can be mounted directly upon the end of the driving shaft of a conventional electric motor.

' Another object ofmy invention is to provide:

a single entry type of centrifugal pump wherein the single entry impeller is provided with spiral passages of substantially uniformcross section on both its front and back with holes connecting the passages on the back with those on the front of the impeller to provide, in effect, a balanced impeller.

Another object of my invention is the provision of a centrifugal pump having a vane type impeller constructed in such a manner that the impact of the vanes on the fluid is utilized to effect a higher range of efiiciency in the pump.

Another object of my invention is the provision of a centrifugal pump in which the impeller can adjust itself axially in the pump casing without loss of eificiency and without effecting rubbing of the impeller on the casing or the disturbances of appropriate clearances between the impeller and casing. This allows the armature of an electric motor'drivingthe impeller to adjust itself centrally of the armature field, and permits the impeller to be mounted directly upon the end of the-motor -shaft.

9 Claims. (01. 102-103) The foregoing objects of my invention, and.

other objects which will become apparent as the description proceeds, are achieved by the pro-1 vision of a, centrifugal pump including a casing,

a single-entry impeller rotatably mounted in the; casing, the impeller having spiral passages of substantially uniform cross section on both front and back, and having holes connecting the passages on the back with the-passages on the front of the impeller. The impeller is generally of fiat,

- disc shape, and has a conical recess in alignment with'the' intake onthe casing, the face of impeller towards the'intake having a plurality of deep, spiral grooves of substantially uniform cross section extending from the conical recess to the edge of disc, the discharge end of each each alternate groove on opposite sides of the impeller. An output conduit is provided on the casingfposition'ed tangentially of the impeller periphery, and a scroll is generally provided in"- the casing of gradually increasing depth in a a direction parallel to the impeller axis and connected to the output"conduit substantially at the point of greatest depth of the scroll.

For a better understanding of my invention, reference should be had to the accompanying drawings, wherein 1 Fig. 1 is a side elevation of the pump and motor assembly of the invention, with a portion of the pump being broken away substantially on line II of Fig. 2;

Fig. 2 is an end elevation of the assembly shown in Fig. 1;

Fig. 3 is an enlarged elevation of the side of the impeller disc remote from the intake. of the p mp;

Fig. 4 is a view similar to Fig. 3 but illustrates the intake side of the impeller disc;

Fig. 5 is an edge view of the impeller disc taken substantially in the direction of line V-V of Fig. 4;

Fig. 6 is a fragmentary cross-sectional view taken substantially on line VI--VI of Fig. 3 and illustratinga shape in cross section of oneof the spiral grooves formed on the impeller;

' .Fig. 7 is afragmentary sectional view taken substantiallyon line VII VII of Fig. 4 and i1-' 3 lustrating the manner in which the holes are employed to connect the spiral grooves on the opposite faces of the impeller; and

Figures 8, 9, and are fragmentary crosssectional views taken respectively on lines VIII-VIII, IX--IX, and X-X of Fig. 2 and illustrating the manner in which the depth of the scroll increases towards the outlet of the pump casing.

Having more particular reference to the drawings, the numeral l2 indicates the base of the pump assembly and formed, for example, from an inverted channel. Angles M are usually secured to the base 12 to allow fastening of the base to the floor or other support. Secured, as by bolts 16, to one end of the base [2 is an angle iron cradle 18 formed with an arcuate upper flange adapted to receive a pump casing 29 of the centrifugal pump, cap screws 22 serving to secure the pump casing to the angle bracket it.

As evident from Fig. 1, the pump casing 243 is formed as two parts, namely, a main body portion 24 and a scroll portion 25 connected together around their peripheries by cap screws 22 (certain of which also function as previously described to connect the pump casing to the angle bracket i8).

Rota-tably positioned within the pump casing 20 is a diso shaped impeller indicated as a whole by the minim-a128, and from 1 it be rec-- ognized that the impeller is positioned about two-thirds of its thickness in a socket portion 3!! in the main body 24 'of the pump casing 25. About one-third of the thickness of the impeller is received in the scroll portion :26 of the pump casing.

As evident from 3., 4, and 5., the impeller 28 is of substantially flat disc shape, and is provided with a hub portion 32 adapted to mount directly upon the :end of the shaft '34 of an electric motor as which is mounted upon the base 12 of the assembly. The impeller 2-8 is provided with a conical recess :38 on the intake conduit '40 secured to the center-of the scroll portion 28 of the easing into which the inlet conduit 40 opens.

Now having continued reference to Figures 3, 4, 5, and 6 of the drawings, the intake face of the impeller 28 is provided with a plurality of circumferentially spaced spiral grooves 44 of substantially uniform cross-section and of considerable depth, a typical cross section of a groove being exemplifiedin Fig. '6. The grooves 44 communicate at their -innermost ends with the conical recess 38 and open at their outer ends to the outer periphery of the disc. The outer end of each groove 44 is spaced 'angularly about ninety degrees from the inner end of the groove. Each alternate groove, which I have numbered 44, extends only about one-third of the way 'out to the periphery of the disc and then is connected by a hole A6 with a. continuationM of thegroove on the backside of the impeller disc. The holes 46 are substantially the full width of the grooves, and of a length about twice the width of the groove. Fig. 7 illustrates the resulting structure rather clearly, and how the :flow .of fluid is almost directly to the grooves 44* on the .backside of the impeller disc.

Figures 3, 9., and 1D illustrate that the scroll portion 26 of the casing '20 is provided with a scroll chamber 59 which iso'f graduallyincreasing depth in an axial direction around the easing being of greatest depth adjacent an outlet conduit 52 connected .into the casing .20 in a .di-

7 to rubbing on the other.

rection substantially tangentially of the periphery of the impeller disc 28.

The main portion 24 of the casing 20 is provided with a hollow boss 54 surrounding the motor shaft 34, and 2. Crane or other seal 56 is carried between the hollow boss 54 and the motor shaft 34.

In the operation of the apparatus, the starting of the motor 36 will first cause the armature of the motor to center itself in the field, and for this purpose the average electrical motor has about one-sixteenth inch end play in its shaft. The impeller 28 has a clearance of about .107" with the casing 20 so that the motor shaft can move the necessary i (.062") without allowing the impeller to rub on the casing. Any change in the axial position of the impeller is not very important. If more clearance is provided in the front than'in the back of the impeller, it simply means that the back will pump slightly more than the front and the average capacity will be about the same for any axial position of the impeller from rubbing on one side This is a real advantage in production assembly as other open type impellers will vary five percent with a shift of .020 in impeller axial position. My improved pump can operate with a total end clearance of .107" with no loss of efiiciency and irrespective of fluid on both sides of the impeller.

of impelleraxial position.

This increase in end clearance is an important advantage in the invention and results from the fact that there is a definite radial outward flow This advantage is even more pronounced when .handling viscous fluids in the pump, such as pure cutting oils.

The fact that, with my improved impeller, fluid is simultaneously pumped from both the front and back of the impeller disc gives the very decided advantage that practically all thrust is eliminated from the impeller, thus enabling the impeller to be mounted directly upon the motor shaft, in the manner described, thereby elimihating the space and cost .of a coupling and of separate bearings in the pump.

In the rotating of the impeller, the vanes (which, in the impeller disc, are the portions of the disc between the spiral grooves) function with an impact on the fluid. The classical theory of impeller design strives to have the fluid enter the impeller without shock, but in my :design, I utilize the shock or impact of the vanes on the fluid and have found that the resulting structure operates at a higher efficiency over a.

wider range of flow.

The spiral passages of substantially uniform cross-section in the impeller have been found to be quite efilcient, not only in utilizing the entering impact, but also in discharging the fluid smoothly into the scroll surrounding .the periphcry of the impeller. Extensive tests have indicated that my improved pump shows an veiiiciency of over forty percent for .a considerable portion of the operating range. This may notseem particularly impressive until it is compared with other conventional centrifugal pumps which are on the commercial market and whichhave effic'iencies of less than half of that indicated for my pump.

From the foregoing, it will be recognized that the various objects of my invention have been achieved by the provision of an improved, relatively inexpensive, and highly .efiicisnt centrifugal pump characterized by a substantially ;bal-

anced impeller in which thrust andclearance problems have been largely eliminated, and in' which the impeller can be mounted directly upon the shaft of an electric motor for driving the same. ,v g

While in accord with the patent statutes I have specifically illustrated and described one best known embodiment of my invention, it is to be particularly understood that I am not to be limited-thereto or thereby, but that the scope of my invention is defined in the appended claims.

I claim:

1. A centrifugal'pump including a casing, a rotary impeller in the casing, an intake in one side of the casing in alignment with the axis of the impeller, the impeller being of fiat disc-shape and having a conical recess in alignmentwith the intake, the flat face of the impellertowards the intake having a plurality of deep spiral grooves of substantially uniform cross section extending from the conical recess to the edge of the disc, the discharge end of each groove'being spaced angularly about ninety degrees from the recess end of the groove, alternate ones of said grooves having only about the first third of their length facing the intake and the remainder of the length of these alternate grooves being on the opposite side of the impeller, the impeller having holes connecting the portions of such alternate grooves on opposite sides of the impeller, an output conduit on the casing positioned tangentially of the impeller periphery, and a scroll in the casing of gradually increasing depth in a direction parallel to the impeller axis and connected to the output conduit substantially at its point of greatest depth.

2. A centrifugal pump including a casing, a rotary impeller in the casing, an intake in one side of the casing in alignment with the axis of the impeller, the impeller being of fiat disc shape and having a conical recess in alignment with the intake, the fiat face of the impeller towards the intake having a plurality of deep spiral grooves of substantially uniform cross section extending from the conical recess to the edge of the disc, the discharge end of each groove being spaced angularly about ninety degrees from the recess end of the groove, alternate ones of said grooves having only about the first third of their length facing the intake and the remainder of the length of these alternate grooves being on the opposite side of the impeller, the impeller having holes connecting the portions of each alternate groove on opposite sides of the impeller, and an output conduit on the casing positioned tangentially of the impeller periphery.

3. A centrifugal pump including a casing, a rotary impeller in the casing, an intake in one side of the casing in alignment with the axis of the impeller, the impeller being of flat disc shape, the flat face of the impeller towards the intake having a plurality of deep spiral grooves of substantially uniform cross section extending from the center to the edge of the disc, the discharge end of each groove being spaced angularly about ninety degrees from the recess end of the groove, alternate ones of said grooves having only about the first third of their length facing the intake and the remainder of the length of these alternate grooves being on the opposite side of the impeller, the impeller having holes connectin the portions of each alternate groove on opposite sides of the impeller, and an output conduit on the casing positioned tangentially of the impeller periphery.

"4.A centrifugal pump including a casing, a-

rotary impeller in the casing, an intake in one side of the casing in alignment with the axis of the impeller, the impeller being of fiat disc shape,

- the flat face of the impeller towards the intake of their length facing the intake and the remainder of the length of these'alternate groovesbeing on the opposite side of the impeller, the impeller having holes connecting the portions of each alternate groove on opposite sides of the impeller, and'an output conduit on the casin positioned tangentially of the impeller periphery.

5.'A centrifugal pump including a casing, a rotary impeller in the casing, an intake in one side of the casing in alignment with the axis of the impeller, the impeller being of fiat disc shape, the fiat face of the impeller towards the intake having a plurality of deep spiral grooves of substantially uniform cross section extending from the center to the edge of the disc, alternate ones of said grooves having only about the first third of their length facing the intake and the remainder of the length of these alternate grooves being on the opposite side of the impeller, the impeller having holes substantially the full Width of the groove and of a length about twice the width of the groove connecting the portions of each alternate groove on opposite sides of the impeller, and an output conduit on the casing positioned tangentially of the impeller periphery.

6. A centrifugal pump including a casing, a rotary impeller in the casing, an intake in one side of the casing in alignment with the axis of the impeller, the impeller being of flat disc shape, the flat face of the impeller towards the intake havin a plurality of deep spiral grooves of substantially uniform cross section extending from the center to the ed e of the disc, alternate ones of said grooves having only about the first third of their len th facing the intake and the remainder of the len th of these alternate grooves bein on the opposite side of the impeller, the im eller having holes connecting the portions of such alternate rooves on opposite sides of the im eller, an out ut conduit on the casing positioned tangentially of the impeller periphery. and a scroll in the casing of gradually increasing de th in a direction parallel to the impeller axis and connected to the output conduit substantjpllv '21-, its rm nt. nf gre te t hfl'l.

7. A centrifu al pump includin a casin a rotar impeller in the casin the im eller being of flat disc shape and having a fiat face facing towards the intake of the pump and having a plurality of deep spiral grooves of substantially uniform cross section exten in from a center recess therein to the edge of the disc, the discharge end of each groove being spaced angularly about from the recess end of the groove, alternate grooves having only about the first third of their length facing the intake and the remainder of the length of these alternate grooves being on the opposite side of the impeller, the impeller having holes connecting the adjacent portions of each alternate groove on opposite sides of the impeller.

8. In a centrifugal pump, a smooth surfaced disc type impeller having similar spiral grooves formed in spaced circumferential relation on opposite surfaces thereof, and with said grooves extending in depth over two thirds of the thickness of said impeller, the said grooves on on surface of said impeller bein of greater areuate length than :the said grooves 01115118 other sunface of same and facing the input of the pump,

said impeller having holes for-med therethrough 5 at the radially inner ends of said shorter grooves, said one surface of said impeller having radially inwardly extending arouate grooves in such surface thereof connecting to said vholes and comprising a continuation of the projections of said shorter grooves to such one surface.

9,. In a centrifugal pump, a smooth surfaced disc type impeller having spiral grooves formed in spaced circumferential relation on opposite surfaces thereof, the said grooves on one surface of said impeller being of greater arouate length than the said grooves on the other surfaee of same, said impeller having holes for-med therethrough at the radially inner ends of said shorter grooves, said one surface of said impeller having radially inwardly extending arcuate grooves in such surface thereof connecting to said holes and leomnrising a 'eontinuation of the projections of said shorter grooves to vsueh one .Sdrfaee.

JAY M. RQTH.

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